1. Field of the Invention
This application relates to polysiloxane compositions grafted with improved heat curable, moisture curable, or heat/moisture curable groups. In particular, the polysiloxane compositions have reactive groups on the terminal or pendent areas of the siloxane backbone, which once reacted provide improved heat and/or moisture curable polysiloxanes.
2. Brief Description of the Related Technology
Moisture-curing mechanisms, heat-curing mechanisms, and light-curing mechanisms are among the means used to initiate cure, i.e., cross-linking, of reactive compositions, such as reactive silicones. These mechanisms are based on either condensation reactions, whereby moisture hydrolyzes certain groups, or addition reactions that can be initiated by a form of energy, such as electromagnetic radiation or heat. In certain compositions, a combination of such cure mechanisms may be used to achieve the desired results.
For example, reactive polyorganosiloxanes can be cured in the presence or absence of heat in the presence of a peroxide. Alternatively, these reactive siloxanes can also be cured in the presence or absence of heat in the presence of silicone hydride-containing (—SiH) compounds and a metallic hydrosilylation catalyst, such as an organo-platinum catalyst.
Dual curing silicone compositions are also known. However, generally, these dual-curing compositions have been limited to compositions that are both light-curing and moisture-curing. See U.S. Pat. Nos. 4,528,081 (Nakos) and U.S. Pat. Nos. 4,699,802 (Nakos), the disclosures of each of which are hereby incorporated herein by reference.
Notwithstanding the state of the technology, it would be desirable to provide a curable composition, where the composition would be curable in the presence of heat and/or moisture, as well as heat and/or light, or moisture and/or light, which demonstrates commercially acceptable tack free time upon curing.